Here HARRY HARPER gets down to the practical mechanics of a lunar trip, and tells of the great space-ship now actually being planned for a voyage to the moon.

I always thing myself lucky that during my life in our world of flying I have had chances of studying so many wonderful machines designed to aid men in their conquest of the air. But I can certainly say that no schemes I have ever looked over before have equalled in sheer fascination those plans and drawings which have been made ready by British experts for a first great man-carrying rocket to carry its crew of three on a pioneer voyage across space from the Earth to the Moon.

When you have seen this wonderful machine taking shape on the draughtsman's board you feel that the word "rocket" is one that hardly fits it. This wonder-craft is something more than that. It is something more than just a projectile. It is more of a ship than a rocket. It is a vessel of an entirely new kind even in these days of mechanical wonders; a machine for doing the one job that has never been done before, and that is to voyage away across outer space. It is, one might say, a space-ship rather than a rocket; a sleek, tapering, gleaming ship of the new era that is now dawning - the era of travel across space.

Picture to yourself a great tubular-shaped machine with a domed head - a machine which, when it is fully loaded for a 240,000-miles flight to the Moon, will weigh as much as 1,000 tons. Right up in the head of this space-flying ship will be the compartment for the crew, with all their many instruments and controls. It is from this "brain" that the crew of three astronauts will navigate their great machine as it rushes across space, governing the speed at which its rocket tubes thrust it upward, and working out their calculations for the navigation of their machine as it speeds across the void at a rate not of hundreds but of thousands of miles an hour.

This space-ship control-room will be a chamber of a kind never seen before. It will be the first room of its type solely for the navigation of space. One of its most remarkable features will be the way in which the crew will be accommodated. Each of these three men, at the moment the giant machine leaves the Earth, will be lying back on a specially designed type of reclining chair. These chairs, or couches, will be built from materials making the specially springy, the idea being to enable the space-ship's crew to withstand, without any bodily shock, the acceleration or starting-off speed of their vessel as it gathers way just after leaving the ground. At they lie back on their reclining-chairs the crew will have arranged for them, quite near them on the arms of their chairs, such controls as will be needed to govern the movements of their vessel just after its ascent; while the three chairs will be so fitted on circular rails, running round the control chamber, that those reclining on them will be able to move themselves to different points of the chamber without needing to get up from their chairs; and these movements they will make to operate such extra devices as are not governed by the controls fitted on the arm of their chairs.

One of the problems which the designers have to bear in mind is not to drive a man-carrying rocket into the air, just after its taking-off, at any too rapid an upward climb. If one did so, this might cause physical injury, and perhaps even death, for those in the control-cabin. In this matter, however, we learned a lot during the war about what the human body can stand in acceleration, or in swift dives, climbs, and other manoeuvres made by fighting-planes. These strains on a pilot's body - "g" pressures, as they are called - have been studied by medical experts, who can now tell exactly what rate is safe, and what might be harmful; and in working out the take-off speed of a moon-flying rocket, and its rate of climb as it rushes up through the Earth's atmosphere and out into space, the figures will be kept well within what is now known the organs of the human body can stand.

Speeds which seem enormous - which seem fantastic when one views them from what we have known, so far, of speeds in land, sea, and air travel - will be reached by space-vessels of the future when on lunar or interplanetary voyages.

It rather took one's breath away when a jet-plane rushed through the air at over 640 miles an hour. But that is merely a jog-trot speed compared with the super-rapid rates which will be attained by space-flying vessels. After leaving the Earth, and by the time it has reached the limits of our atmosphere at a height of about 200 miles, it has been calculated, for example, that a first man-carrying lunar rocket will be rushing up at something like 10,000 miles an hour; while when it is in outer space, on its way to the Moon, it will go on gathering speed till it is travelling at about 20,000 miles an hour.

Nor are these figures, amazing though they are, anything like a limit. They have been worked out for space-vessels driven by any kind of fuel-power such as we have today. But if in the future we can get atomic-driven space-ships, their highest speeds when on interplanetary voyages may, it is thought, go up to something over 100,000 miles an hour!

What about the effect of such colossal speeds on those inside a space-ship?

Well, as I have already said, the point here is to keep the rates of acceleration or deceleration - of speeding-up or slowing-down - within such limits as medical experts can now fix for us. Once you have built up your speed gradually, and are in full flight out there in the vastness of space, it will not matter to those inside a rocket whether they are moving at 10,000, 20,000, or even 100,000 miles an hour. Provided there are no violent changes of speed from fast to slow, or slow to fast, they will have no means of telling, beyond what their instruments say, what their actual rate of travel is at any given moment.

When you are very high up in an aeroplane, and even if you are moving at hundreds of miles an hour, your movement may seem very slow when you look down on the Earth far below. It is the same if you are inside any enclosed vehicle, and have on rush of air round you to tell you the tale of speed. Unless your eyes, by the flashing past of objects outside, give, you an idea of how fast you may be moving, there is nothing except instruments that will tell you what your actual speed may be. And it is here, by the way, that my friends who study the stars remind me that all of us on this Earth are travelling round the Sun at a speed of as much as 18 miles a second. Yet none of us is aware of this by any bodily sensation, nor do any of us feel any the worse for it.

When you look into the design of the big lunar rocket, or space-ship, which I have just been mentioning, one interesting thing strikes you. You see that this machine in not really just one rocket, but that is is several different power units, all connected together to form one vessel, and yet each being distinct in itself.

The idea of this system of separate power-compartments, or units, is to get as much power as possible, and at the same time, to save every pound of weight that can be saved - the great problem being to have enough fuel to get you to the Moon and back and yet not to have a machine which is too big or too heavy.

Until we get atomic power, our experts plan to use some improved liquid or solid fuel system, and in the design I am writing about here the idea is to use some plastic chemical fuel which, when ignited, will give to the rocket the biggest possible reaction thrust.

The exact ingredients of such a fuel will have to be decided by further researches. Already British experts have studied 80 or more different plastic or solid fuels, and there is still much further work on hand. But if we take it for granted, here, that some definite fuel has been chosen, something of a plastic nature, then for driving our rocket this fuel will be packed into a large number of separate tubes- or one might perhaps call them "cartridges." Groups of these tubes will be brought together, in honeycomb plan, to form what designers call a "step" or complete section of the big rocket.

Of these "steps" there will be six. They will extend one above another from the stern or bottom of the rocket right up to the domed head with its control-room. Each honeycomb of tubes will be circular in shape, and will be made up of a very large number of tubes, all of them packed closely together, and held together by an outer skin, or sheath, of light metal. Each section or compartment will be attached to the next. So you have a machine which is in six different sections, one behind the other, and each with its battery of driving tubes.

The whole idea of this "step" system it be able to pack the largest amount of fuel, or driving power, into a long-distance rocket machine and, at the same time, to avoid having to carry a lot of useless dead-weight after the batteries of fuel-tubes have used up their contents.

Just at the moment the 1,000-ton rocket starts from the Earth, at the beginning of its flight, sometimes like 90% of its total weight will be made up of the rocket tubes and their contents, leaving only 10% for the crew and their equipment. But as the great machine climbs skyward in will become lighter, and not only lighter but smaller.

This will be brought about in the following way.

When the machine takes off, the lowest of the circular "steps," or honeycombs of rockets, will be fired electrically by those up in the control-room. As each rocket tube gets rid of its contents it will drop away automatically from the machine. When all the tubes of the bottom step have done their work, and the rocket is climbing rapidly, the sheathing or outer covering of this "step" will also drop away, freeing the rocket completely of the dead-weight of the spent tubes and their covering.

Directly the lowest of the six "steps" has finished its work, the control-room crew will switch on the fifth or next "step." This, in turn, will fire all its tubes and drop away from the rocket.

So it will go on until, when the vessel in nearing the Moon, there will be only one step left. This will be the top one, at the head, in which will be the control-room of the crew. It will be this final section of the rocket - a much smaller and far more easily handled machine than the 1,000-ton projectile which first left the Earth - that will make its landing on the Moon. This sixth and last "step" will, it is reckoned, have enough fuel for the return flight of the rocket from the Moon to the Earth.

The reason so much less power will be needed for the homeward than for the outward flight is to be found in the fact that the force of gravity on the Moon is only about one-sixth that of the Earth. This means that it will be much easier for the rocket to free itself from the gravitational influence of the Moon, with less fuel necessary for the climb away from the lunar surface.

The voyage across to the Moon will fall into two stages.

During the first stage the space-vessel will be using its power to free itself from the Earth's gravity pull. In the second stage it will have come within the influence of the Moon's gravity, and this will mean that instead of accelerating or using its climbing power as it had been doing to get away from the Earth, the machine will now have to begin to slow-up, so as not to come into too violent a contact with the surface of the Moon.

It will now be that the crew will carry out the following manoeuvre.

By a use of certain extra rocket tubes with which their machine will be fitted, they will turn their vessel round very slowly, a few degrees at a time, until it is facing stern-first towards the Moon. Then, bringing their main rocket batteries into play again, they will use these to slow-up their vessel as it is being drawn towards the Moon under the gravity pull of that body.

In this way, by decelerating or braking their vessel as much as may be needed, they will draw nearer and nearer the Moon until they make a contact with its surface at a speed slow enough to be taken up by the landing chassis with which the space-ship will be fitted, and which, when not in use, will lie housed along the sides of the machine. This landing device will be specially designed, with shock-absorbing legs, on which the rocket will stand when it has made its contact with the Moon. This same chassis will also serve as a launching platform when the time comes for the explorers to leave the Moon on their return to the Earth.

Once safely on the Moon's surface, the three astronauts will put on their special helmeted "space-suits." These will be something like a diver's suit, but will be much lighter and easier to move about in. There being no air on the Moon, the suits will have a special breathing apparatus. They will be also fitted with heating devices to prevent their wearers feeling the extreme cold they may have to face while making their surveys on the lunar surface. These explorations will take the form of a search of geological and mineral specimens, which the party will carry to their machine so as to bring them back with them for further study by scientist on their return to the Earth. They will also take photographs, and make a number of special scientific observations.

One fact in their favour, while moving about on the lunar surface, and in handling any objects they may wish to move or carry, is that the lower force of gravity of the Moon, as compared with that of the Earth, will make it easier not only to move here and there, but also to pick up or transport anything they may want to bring back and place in their machine.

As for their actual landing again on this planet at the end of their lunar voyage, what is most likely is that as they near the Earth they will release from the domed head of their rocket a very large parachute. This will be big enough to waft down to a safe and smooth landing the entire top part of the rocket, with the crew in their control-room, and such geological specimens and other objects of interest as they have brought back them from the Moon.

There is one thing you need to bear in mind about this Moon-flying project.

It is that all that has been worked out, so far, is quite open to change and alteration in all sorts of ways as further light is thrown on many of the questions that crop up.

There is that important question of what can be done in using atomic power in driving a space-flying vessel. If we can get atomic energy in a controlled and practical from, then its force will be so enormous compared with that of any other known power that we shall be able to make more simple, in a good many ways, the design of a lunar space-ship. There will not be any need to have to allow for such a huge weight of fuel; while the inside of the machine can be made to give more space and comfort for the crew who will be in it. Atomic power should also mean such colossal speeds, while on space voyages, that a trip across to the Moon might be made in a few hours; while instead of lasting weeks, as had been reckoned with a machine having any of the fuels we could use at present, journeys to Mars or Venus, in an atomic-driven rocket of the future, may be shortened to a matter just of days.

Already those who are making a study of atomic power are beginning to see ways in which this titanic energy can pour out in a controlled stream instead of being released just in one enormous discharge. One plan is for the injection into a special combustion chamber, one after another, of a series of very small charges of that particular part of uranium which forms our present source of atomic power, and which is known, scientifically, as one of the "isotopes" of this metal.

In this combustion chamber the atomic energy of each of the charges would be released, and their terrific power shot out from the rear of the rocket in a stream of atomic particles travelling at enormous speed.

There are other ways, too, in which it is thought atomic energy may be controlled and made to do what man wants it to do. One takes the form of what is known as an "atomic generator." In this, uranium has mixed with it a certain amount of graphite, which has the effect of moderating and controlling the rate at which the energy is released. Contained in a tank fed with water, the substance becomes incandescent, or glowing, when brought under the influence of those particular "neutrons," or particles, which have the effect of releasing the stored-up atomic energy. This result is that the water in the tank is condensed into steam energy or power, which can be used either in driving a turbine, or in running any other form of engine.

Yet another method of slowing-up the release of atomic power is by using certain metals which "neutron" particles cannot penetrate. These metals are make to "sleeve" or protect the atomic substance, and by allowing only a certain part of it to be exposed at a time they have the effect of controlling the atomic discharge.

When you talk over the designing of space-ships with those who are getting to grips with all the questions in this new kind of engineering, you find there are things cropping up which have never had to be tackled before. Many are about the special instruments which the crew of a space-vessel will need in handling and navigating their machine on a voyage to the Moon, Mars, or Venus.

Take the question of having some instrument which will tell you the speed of one of these great machines of the future as it rushes across space.

Here you come upon an interesting point. It would be useless, in any machine for the navigation of space, to rely on any such speed-indicators as are used in aircraft, and which rely for their working on air pressure. They would fail to do their job simply because out in space there would be no air pressure to act upon them. This means that designers have had to plan a new kind of speed-indicator for space-ships. This will not rely on air pressure but on momentum, on the acceleration or swift forward movement of the space-ship in which it is fitted, and this will affect a delicate internal arrangement of springs, weights and magnets.

That is just one of the man questions cropping up in space navigation.

Here is another.

When a machine gets into outer space, beyond the Earth's atmosphere, it will have on one side a fierce heat from the Sun, while on the other there will be very severe cold. To cope with this, and to stop one side of the space-vessel becoming much too hot, while the other is much too cold, the whole machine will be made to rotate or spin round very slowly as it flies, this quite slow spinning movement preventing any part of the vessel becoming either too hot or too cold. The machine will, it should be added, spin round so slowly that no ill-effects will be felt by the crew in their control-chamber.

There will be another advantage from making a space-ship spin round slowly as it flies. This will be in the fact that a certain centrifugal force will be brought into play by the rotation of the vessel, and this, in its turn, will lead to a form of artificial, self-contained gravity, or a feeling of weight, for the members of the crew inside their control-room. The effect of this centrifugal force, or antisocial gravity, will be to make up for the lack of any such gravity force while the vessel is travelling through outer space.

It often happens with the design of such a new kind of machine as a space-vessel that you get the answer to one question only to be faced by another. This is the case in the plan to make a machine spin round slowly. This may be the answer to the over-heating or over-cooling of your vessel's hull, but it brings you up against what happens when the crew, while on a voyage across space, want to make navigational observations to help them check the position of their machine. To make any such observations properly you need a stationary platform - something that is standing still - to use your instruments form, not anything that is revolving all the time.

Our designers, however, did not let themselves be beaten by anything like this. They just went into a huddle and came out of it with plans for a wonderful piece of mechanism called a "coelostat." Without going into a lot of details, one may say that this instrument uses mirror-driven devices, and that by means of these mirrors, some of them moving and others standing still, it will be possible for navigational purposes for a stationary view of the heavens outside a space-ship to be gained b those inside its control-room, even while the machine itself continues to spin round slowly.

There is actually another over-heating question that will have to be borne in mind, apart from the one when a rocket is in outer space. This would occur in the period while the lunar vessel was rushing up through the Earth's atmosphere, and just before it came out into space. Owing to the terrific speed of the machine as it thrust upward through the air belt surrounding the Earth, a very intense frictional heat would have to be reckoned with just at the head or nose of the rocket, and this would need to be dealt with by some special means, so as to prevent this over-heating from becoming serious.

What is put forward as a remedy for this? The idea is for the nose of the rocket, when it leaves the ground, to be protected or insulated by an outer sheathing or skin which would take the form of some special heat-resisting material. This false 'nose" would be so fitted, in sections, that after it had served its purpose, and the rocket had passed out beyond the Earth's atmosphere, with frictional air resistance no longer to be bothered about, the crew of the machine would be able, by using a suitable release device, to cause the nose-piece to open out and drop away from their machine.

In the head or nose of the rocket, just where the control-room is, there will be a number of port-holes, or out-look windows. These will be placed so as to give the crew, when they are making their observations with sextants and range-finders, a clear view ahead and sideways, and also astern of their machine.

One should mention that to keep the rocket stabilised, or balanced, as it ascends, and to keep it in its proper direction, there will be a gyroscopic apparatus which will work automatically inside the machine. Also, fitted in the control-room, will be a pendulum device to give the crew warning should their vessel begin to swerve or wobble in any way as it climbs.

One of the questions one hears space-flight experts talking about is at to the method which will be used in launching a big lunar vessel on a first flight to the Moon. Here, putting things simply, there are two main ideas.

One is for some device which will send the rocket up from a platform fixed up somewhere on land. The other is for a launching stage floating on water, such as the surface of a lake. One scheme already put forward is for a big floating stage to be taken out in sections to Lake Victoria, in Africa - one of the ideas for starting from this famous lake, experts explain, being that there would be certain advantages, from a navigational point of view, in beginning a flight to the Moon from somewhere round about the Equator.

I have been looking over a design for a floating rocket stage such as might be used on Lake Victoria. It would be built of concrete in sections, and it would have a big central tube, or shaft, going down below water level. In this tube the space-vessel would be placed in an upright position before starting, just like some huge projectile in a gigantic gun.

One of the features of the floating stage would be that it would be fitted with special buoyancy chambers to take up the recoil which would have to be reckoned with at the moment when the space-vessel began to surge up at the start of its flight.

Even after you have designed and built a space-machine, and have got all your instruments for navigating it on a voyage across space, there are still questions on which further light will need to be thrown.

Take those much-talked-about cosmic rays. Ways are they? Well, these are the rays about which, coming as they do from somewhere or other far in outer space, a good deal more needs to be known than anybody - even our scientists - can claim to know today. Consisting as they do partly of tiny, very highly charged electric particles, these rays, though we cannot seen them and cannot feel them, have an effect on the human body in different ways. The belt of atmosphere all round our earth has, however, a softening or weakening effect on the rays. But the question yet to be answered is what effect these cosmic rays might have on the crew of any space-vessel after that machine had moved into outer space, and was not protected any longer by the Earth's atmosphere. Here, already, some useful hints have come to us from high-altitude balloon ascents, and more facts will be got by sending up to immense heights some of our special "sounding" rockets. So far as our experts care to say at present, it does not look as though cosmic ray ought to have much effect, one way or another, on those who go voyaging across space.

Another point which crops up, but about which my space-flight friends say they are not worrying very much, is as to the chance of any man-carrying rocket, while on a voyage through space, coming into collision with a meteorite - one of those bodies, large or small, and consisting chiefly of iron or stone substances, which rush here and there space at tremendous speeds, and which may perhaps be portions of matter which have become detached in some way from the planets.

If a space-ship did collide with one of these meteorites, it might certainly be very unpleasant for those inside the vessel. But let us see what the chances are of anything like that happening. Of course it is known that these meteorites are dashing about here and there far out in space. But what you have to bear in mind is this. Space out there beyond our Earth is so immense, so vast, and the distances between one planet and another so huge, that even if there should be any meteorites darting about the chance of a collision between a space-ship and one of them would be very small indeed. It would, as one of experts has worked out, be something like a million to one against such a collision ever taking place.

So our space-flight men are not worrying their heads very much about this peril. They have other things more important to think of. Even the remote chance of being hit by any meteorite may be guarded against by fitting a space-ship with a special "radar" or radio-location wireless set, which would give the crew warning if any fast-moving object like a meteorite was approaching. This would give a chance of altering course to avoid any risk of a collision.

The ever-growing wonders of wireless will play their part in all sorts of ways in the coming conquest of space.

Already our scientists have been able to report how special long-range radio-beams, sent out beyond the Earth's atmosphere, have flashed across space, not only to the Moon but also as far as the Sun, and by coming into contact with these bodies have given rise to return "echo" signals which have come back to this Earth and have been received quite clearly and distinctly.

It will be by some special system of wireless, linking those away in a space-ship with a station here on Earth, that our first voyages to the Moon will be able to report their progress from hour to hour as their machine rushes far out across the void, and it will be a wonderful moment for listeners here on Earth when at length a message comes through from those first space-voyagers to say that they have actually reached, and have landed safely on, the surface of the Moon.

Perhaps, when that day comes, and we are sitting in our homes listening to the wireless, we may hear an announcer cut in suddenly on one of the B.B.C. programmes to ask us to stand by to hear a spoken message coming to us actually from the Moon itself, in which one of these first men to put foot on its surface will be able to tell us, from a quarter of a million miles away, just what he has been doing, and what he has been seeing, away out there on those mountains and valleys of the Moon.